where the trunk is damaged there was another branch comming off. somebody ripped it off it looks like instead of cutting it. its kind of like cutting a plummeria. wherever you cut will scar and a new branch should form. looks like what you have there is a cutting off the side of another plant. it was ripped of the other plant then rooted in another pot. you can clean up the side but cutting the dead away in a uniform matter. you can cut the dead leaves off even the ones that are browning. dont go too crazy were comming into fall and growing season is over. dont want to shock the plant. wish i had one of these so i could make a vid and show you. it would be easier to explain.